After writing "The Last Light of Dusk," Joanne Lockyer got friends to pose for the cover (left).Blueberry Hill Productions

Joanne Lockyer may be a born-and-bred Australian, but her love affair with romance novels is an all-American obsession.

“I like to say I fell in love with romance novels in the back of a rental car on the US interstate,” Lockyer, a 36-year-old resident of Brisbane, Australia, tells The Post. She was 15, and her family had embarked on their first international road trip when, somewhere outside of Detroit, she ran out of reading material. “We were visiting a family friend, and she brought out this big box of books full of worn historical romances and said, ‘Take what you like.’ ” Lockyer tore through her collection across Illinois, South Dakota, Wyoming and Colorado. “I was swept away by the stories.”

Lockyer is one of six women profiled in “Love Between the Covers,” a documentary about the $1 billion romance novel industry. The film, which will be released on video on demand Tuesday, offers a glimpse of the lives of authors who write these books — but Lockyer’s presence in the film sticks out as an anomaly. She’s at least a decade younger than her peers, plus she was the only one to be unpublished at the time of filming.

Lockyer is the only newbie author in the romance novel doc “Love Between the Covers.”Courtesy of Joanne Lockyer

Lockyer started writing romance novels in 2006, after completing a master’s degree in law and getting a job as an environmental consultant at an energy company in Brisbane. “They were an escape for me during my studies, and I even tried to write a few stories in school, but I didn’t have enough life experience,” she says.

She would wake at 4 a.m. to work on her character arcs and story outlines before heading into the office. “I had to do a lot of research, looking at period journals and Regency fashion plates and even shipbuilding documents.”

The result, “The Last Light of Dusk,” took about eight years to finish and follows a headstrong shipping heiress who falls in love with an English seafarer during the aftermath of the Napoleonic Wars.

But finishing the story was just the beginning. Lockyer opted to self-publish. She hired an editor, but did everything else herself — including developing a website, doing promotion, getting ISBN codes and registering for a copyright. “I invited my friends over for a photo shoot and dressed them up in Regency costumes for the cover. It was hilarious and fun,” she says.

Though she won’t disclose how much money she’s made from her novel, she does get 70 percent of the royalties from Amazon sales. (An author with a book publisher usually gets 12 to 15 percent.) Typical contracts for new authors range from $1,000 to $20,000, while established authors such as Nora Roberts can make millions per book.

Lockyer’s currently sketching out a follow-up, but she’s not banking on a career in romance yet.

“I can’t handle the deadlines,” she admits. “But I’m really proud to be part of this genre that represents such a wonderful women’s community. And to be in the same documentary as Nora Roberts and all these other women who made such a mark. It’s really complimentary.”